php - Change array values based on a reference array

Solution:

Just flip the array of genres and compute the intersection of the keys. With your current code:

$return['movie_genre'] = array_intersect_key($references,
                             array_flip($return['movie_genre']));
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Or combined:

$return['movie_genre']= array_intersect_key($references,
                            array_flip(array_map('trim', explode('/', $genre))));
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If you really need those integer keys:

$return['movie_genre']= array_values(array_intersect_key($references,
                            array_flip(array_map('trim', explode('/', $genre)))));
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Or to combine with yourarray_map to lookup the reference key from the value:

 $return['movie_genre'] = array_map(function($v) use($references) {
                                        return $references[trim($v)];
                                    }, explode('/', $genre));
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And for fun with your current code; flip the reference array and grep for the genres and get the keys:

$return['movie_genre'] = array_keys(
                         preg_grep('/^'.implode('|', $return['movie_genre']).'$/',
                         array_flip($references)));
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All that being said, I would probably do this:

foreach(array_map('trim', explode('/', $genre)) as $v) {
    $return['movie_genre'][] = $references[$v]; // or trim() here instead
}
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Solution:

Utilizingarray_map and arrow functions:

$result = array_map(fn ($genre) => $references[$genre], $return['movie_genre']);
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Note that for versions prior to 7.4, when arrow functions were introduced, you'd have to write an anonymous function:

$result = array_map(function ($genre) use ($references) {
    return $references[$genre];
}, $return['movie_genre']);
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You can easily substitute$return['movie_genre'] with your existing one liner.